Mixing in Monero is instantaneous.
Sure, there's a learning curve that goes with using the command line/terminal - but it's time well spent it if it saves you from having to wait hours every time you need to mix. And then you know how to use a command line/terminal!
Dash separated transaction mixing back in the summer of '14.
Initially it required mixing while sending, where you'd wait for others to mix and send.
Post-summer '14, it works with
premixing the coins (when you don't want to transact) so that when you want to transact later => it's instant / you are sending pre-mixed funds. It's a nice workaround.